The Chinese consulate in San Francisco has said its compound was damaged in an arson attack and urged American authorities to protect the safety of its diplomats and its premises.

The consulate said in a notice on its website that a person came out of a van parked outside the compound on Wednesday night with two buckets of petrol, poured the fuel on the front door of the consulate building and set it on fire.

The consulate's notice, which was in Chinese, did not identify the individual or say how the consulate knew what had caused the fire.

The notice said the fire caused serious damage and that San Francisco's police and fire departments attended the scene.

The notice called the incident "a sabotage of a vile nature" and said China had urged US authorities to launch an immediate investigation. It also said an investigation was under way.